Cellular networks, such as global systems for mobile communication (GSM) and general packet radio service (GPRS) mobile service networks, provide two-way voice and data communication with regional, national or international coverage. This makes mobile communication very convenient. These networks, however, use powerful base stations to communicate with mobile terminals making mobile communication expensive. An alternative to expensive cellular networks is wireless local area networks (WLANs), such as Wi-Fi (e.g., Institute of Electrical and Electronics Engineers (IEEE) 802.11). Unlicensed Mobile Access (UMA) technology provides seamless access to a cellular network over Wi-Fi or other unlicensed spectrum technologies.
A dual-mode enabled mobile terminal, such as a UMA-enabled mobile terminal, or a mobile phone or computer with cellular and wireless functions, can switch between a cellular network and a WLAN. However, it is typically limited to accessing a WLAN with free access, a WLAN supplied by the cellular network service provider or a WLAN with a known access code. For example, some service providers have installed WLANs, called hotspots, in public places, where their own subscribers are allowed to connect after paying for such service and entering an access code. Non-subscribers, however, cannot access these hotspots. Not only does this limit the number of locations of available service but in some cases, it results in networks being underused.
An important point to remember is that UMA takes care of the seamless connection of a dual-mode device from a cellular system to a WLAN, once the device is successfully associated with WLAN. For example, a user makes a voice call or a data connection by a dual-mode cellular handset over the cellular wireless network. When the user goes to an authorized hotspot area, the phone can switch to the WLAN, i.e., the hotspot. At this point, UMA ensures that the call can be continued over the WLAN seamlessly. However, UMA does not address how to access Wi-Fi networks, it just provides the seamless connection once the physical wireless connection is achieved, such as through successful association with a hotspot, a home or a free to public WLAN.